Process for heat-treating milk and cream



J O- FOWLER PROCESS FOR HEAT IREATING MILK AND CREAM Jan. 3, 1950 3 Sheets-Sheet 1 Filed March 26, 1947 Jan. 3, 1950 J. o. FOWLER PROCESS FOR HEAT-TREATING MILK AND CREAM .Filed March 26, 1947 3 Sheets-Shem. 2

Jan. 3, 1950 .1 o. FOWLER PROCESS FOR HEAT-TREATING MILK AND CREAM Filed March 2a, 1941 3 Sheets-Sheet 3 Patented Jan. 3, 1950 PROCESS FOR HEAT-TREATIN G MILK AND CREAM James 0. Fowler, Sparkhill, Birmingham, England Application March 26, 1947, Serial No. 737,260 In Great Britain April 11, 1946 3 Claims. 1,

This invention has reference to a new or improved process for heat treating milk and cream and has for its object to improve the process described and claimed in the specification of my pending U. S. application Serial No. 637,061 filed on December 22, 1945.

According to the present invention the process for the heat treatment of lacteal fluids resides in filling the fluid either cold or after a preliminary heating in bulk into bottles, capping the filled bottles, assembling a plurality of filled and capped bottles into a batch and subjecting each such batch individually and successively by intermittent step by step progression firstly to heat treatment by complete immersion for a prescribed period of, time in a vessel containing a heated liquid preferably hot water maintained at a prescribed temperature, then to removal from the vessel in which heat treatment takes place and to submissionto an initial cooling of relatively short duration by. immersion in a liquid preferably water, the temperature of which is somewhat below the temperature at which heat treatment is efiected but considerably above the temperature of subsequent main cooling said initial cooling affording an opportunity for the conditioning of the walls of the bottles prior to the main cooling and subsequently to cooling by immersion for a prescribed period or successive periods of time in a liquid preferably water maintained at a prescribed temperature.

Figure l is a diagrammatic representation illustrative of the method of carrying the invention into effect.

Figure 2 is a diagrammatic representation of a modified form of tank which may be utilised for heat treatment purposes in connection with the method illustrated in Figure 1.

Figure 3 is a diagrammatic representation of a heat exchanger arrangement for use in conjunction with the process illustrated in Figure 1.

In the drawings like numerals of reference indicate similar parts in the several views.

Dealing first with Figure 1. v

The raw milk as received is emptied into the tank 4 from which it is forced by a pump 5 through a filter 6 of known construction. 7

The filtered milk is then'passedrby afloat controlled constant level vessel 1. to thelsupply tank of a bottling plant of the vacuum filler type of 2 known construction indicated by the reference numeral 8.

In this bottling plant 8 the bottles 9 are filled to a level which allows for expansion during the heat treatment. After filling the bottles 9 are passed to a capping machine of known kind which is denoted by the reference numeral Ill and which caps the bottles with caps 9a conveniently of the kind known in commerce as crown seals.

After sealing the bottles 9 are placed in partitioned .crates of known kind and a number of crates constituting a batch, say 27, are then placed in a cradle 12.

At the appointed time this cradle I2 is hoisted by an electric winch and subsequently lowered into and immersed in one or other of the tanks 130,, I31) containing water which is heated to a temperature of F.- F.

The electric winch, not shown, incorporates a two speed gear which permits immersion to take place slowly.

The capped bottles 9 and contents are held in one or other of the tanks l3a, l3b at the temperature aforesaid for a period of 30-35 minutes after which a cradle l2 with its load of bottles is removed from the tank l3a or [3 b and is lowered into a cooling tank I 4 containing water at a temperature of 1lO-l20 F. preferably 115 F. where the bottles are held for a period of 5-10 minutes.

The degree of cooling thus effected produces a cooling effect on the structure of the bottles 9 which allows 0f the outer layers of the bottle walls contracting before the inner layers and thus minimizes the risk of fracture of the bottles due to too rapid cooling.

Further this initial cooling prevents the formation of a skin on the surface of the milk in a bottle 9 and so eliminates the possibility of impairing the taste of the treated milk which would otherwise obtain if this formation of skin was allowed to take place.

After immersion in the preliminary cooling tank [4 for the period stated the-loaded cradles [2 are transferred by means of the electric winch to a cooling tank l6 where the bottles remain immersed for twenty minutes in Water at a temperature of 75-85 F. At the end of this time the cradles l2 and bottles 9 are transferred to the chilling tank I! containing water at a temperature of 40-50 F. The bottles are maintained in this chilling tank I! for a period of 15 minutes after which they are removed and are ready for transfer for sale or storage.

As is illustrated in Figure 2 a holding tank I311, I312 in which heat treatment is effected is provided adjacent to one end with a baflie I30 and disposed within the space l3d between the said bafile [3c and the presented end of a tank I3a, [3b are the inlet and outlet pipes [8a, [8b respectively which are associated with the cir culating pump l9.

The inlet orifice of the inlet pipe I8a is arranged to open into a tank l3a, l3b slightly below the surface level of the water in a tank I3a, l3b' when there are no crates immersed therein whilst the outlet pipe 182) is arranged with part of its length parallel to the bottom of a tank and with its outlet orifice located about three inches above *-the bottom of a tank.

During the holding period in a tank 13a, I3b the respective pump P9 is brought into operation so that hot water is drawn from the higher levels and transferred to the bottom levels where the discharged water passes along the bottom of a tank l3c, I31) and subsequently diffuses upwardly vents damage to the inlet and outlet pipes 18a, I81) and to the bulbs 20a of the visible indicating and recording instruments 2|] during the placing of or removal of bottles in or from a tank I3a, I3b. It will be appreciated also that a pump I!) may be used for filling and emptyinga tank 13a, I3b and'ior removing surplus water and passing it to a storage vessel for re-use if required.

Conveniently the milk is preferably preheated in the supply tank of the bottling machine 8 and preferably asshown in Figure 3 this is done by a heat exchanger in which water from the tank I6 is passed through a jacket 2| which is located around 'a .coil 22 from which filtered milk is circulated intothe inlet and 22a of the coil 22 and after traversing the said coil 22 is passed from the outlet end 221) to the supply tank of the bottling machine 8,

The tank I6 is also provided with a thermostatic valve 23 tor admitting water to balance the temperaturein the said tank l6.

The water is circulated through the jacket 2| of'the heat exchanger by a pump 24 and it is found that by circulating through the coil 22,

milk received at a temperature of42 'F. the milk fed to the supply tank of the bottling machine 8 'is heatedto'a temperature of 62F.

Similarly the tank l4 may beadapted by heat exchange to provide warm water for bottle washing for which purpose water from the tank I4 is circulated by a'pump 25 through a jacket 25 containing a; coil 21 into which water from the town mains enters at the inlet end 21a at saya temperature of 55 F. and leaves at the outlet end 21b at a temperature of 85, F. a

Thetank I4 is; provided with a thermostatic steam valve'ZB for the admission of balancing steam. V v

It will be appreciated that in accordance with the present invention also there is no possibility of contamination after bottling and that the subsequent process enables heat treatment to be carried out efliciently without risk of fracture of the bottles or the formation of skin on the surface of the milk after treatment.

It will be appreciated further that the invention is not limited to treatment at the temperatures or for the periods stated as these may be varied as may be required and that the process may be applied also to the heat treatment of cr am which previ us y has een separat d from milk..

I claim:

1. A process for the heat treatment of lacteal fluids, comprising, filling bottles with the fluid to be treated, capping the bottles with liquid proof caps, assembling a plurality of filled and capped bottles as a separate batch, immersing each such batch individually and successively by intermittent step by step progression into each of a plurality of separate water baths, and maintainby heating to a pasteurizing temperature for a period of time necessary to destroy bacteria and then cooling to s orage temperatures that is characterized by the steps of filling containers with untreated fluid, capping thecontainers with liquid proof caps, assembling the capped containers in batches and subjecting each batch successively in intermittent step by step progression to a predetermined series ofimmersions in separate liquid baths, each of the baths being maintained at a substantially constant temperature, the baths being successively at pasteurizing temperature, pre-cooline temperature and cool-' ing temperature, each batch being held substantially motionless relative to each bath, whereby the heat exchange between the fluid containers and the liquid in each separate bath is enacted principally by conduction and the shock to the containers thus kept within" limits to obviate breakage. r r

3. A process for the treatment of lacteal fluids by heating to pasteurizing temperature for a period of time necessary to destroy bacteria and .then cooling to storage temperature by separate cooling steps that is characterized by the steps of filling glass containers with untreated fluid, capping the containers with liquid-tight caps, assembling a group of filled, capped containers in a batch and subjecting each-batch, as a unit, in intermittent step by step progression, to total immersion successively in separate individual water baths, each bath being distinct and maintained at a substantiallyconstant temperature,

' t the baths being first, a pasteurizing bathhaving a temperature of about 150 F. in which each batch is immersed for a period of time suiiicient to effect pasteurization, second a pre-cooling bath having a temperature of about 115 F., third a cooling bath havinga temperature of about F. and finallya chill bath havingajzemperature 6 of about 45 F., each batch being retained substantially motionless in each of the cooling baths UNITED STATES PATENTS for a period of time necessary to effect heat ex- Number Name Date change by conduction to substantially equalize 727,575 rkho May 12, 1903 the temperatures of the bath, containers and fluid 5 749,547 Fesenmeie! 4 and then being moved to a successive bath. 1,004,385 W Oct. 3, 1911 J, FOWLER 1,005,854 Lindemann et a1. Oct. 17, 1911 1,077,270 Gettelman Nov. 4, 1913 REFERENCES CITED 1,227,101 Wehmiller May 22, 1917 10 2,282,187 Herold et a1. May 5, 1942 The following references are of record in the file of this patent: 

